In a trunked system, location information such as information received from a global positioning satellite (GPS) may be sent by a radio on a control channel or on a traffic channel. However, this may overload the control channel and may impact, for example, voice usage on the traffic channel. The location information (also referred to as GPS data or GPS information) may also be sent on a dedicated data channel (also referred to as a GPS revert channel or a revert channel). The GPS revert channel may be windowed or not windowed; wherein when the GPS revert channel is windowed each radio is assigned a specific time window to send the GPS data on the GPS revert channel. Subsequent to sending the GPS data in the specified window, the radio returns to the control channel. However, when the radio is on the GPS revert channel and away from the control channel, the radio is unaware of new calls that were started while the radio was away from the control channel. As the location information reporting increases, the time the radio spends away from the control channel also increases. When the radio returns to the control channel, the control channel sends reporting messages that lists all of the calls in progress. A radio may be affiliated with one or more talk groups such that the radio is interested in receiving calls associated with the affiliated talk groups. Using this approach, depending on the number of traffic channels supported by the control channel, a period of time, for example, a few seconds, may elapse before the radio becomes aware that a new call the radio is interested in receiving was started while the radio was away from the control channel. Therefore, the radio may miss the beginning of those calls started within the duration when the radio was away from control channel for GPS transmission.
Accordingly, there is a need for a method and apparatus for informing a radio about a group call that was stated while the radio was away from the control channel.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.